The politician Sir Marmaduke Coghill (1673-1739) was one of the pillars of the 'Protestant ascendancy' in early eighteenth-century Ireland. His surviving correspondence, drawn from a variety of sources in Ireland, England and the U.S.A., reflects the broad range of his interests not only in politics and government, but also in trade and economic development, in the affairs of Trinity College, and within the private sphere, in promoting innovation in architecture, gardening, and the consumption of luxury goods. In exposing the milieu of a 'man of business' with influence on almost every facet of Irish public life in the period, these letters offer a flood of new information and revealing insights into the 'official mind' of the Dublin Castle administration in the age of Swift.